A recent study published in The BMJ has revealed that high-dose psilocybin may be more effective than traditional antidepressants, such as escitalopram, in alleviating depressive symptoms. Although the effect size of psilocybin was noted to be smaller than initially reported, it still outperformed escitalopram when compared to a placebo.
Psychedelics in Depression Treatment
Psychedelics, including psilocybin, ayahuasca, lysergic acid diethylamide (LSD), and methylenedioxymethamphetamine (MDMA), have gained attention for their potential to treat depression by enhancing neuroplasticity. However, while previous meta-analyses have suggested large effect sizes, concerns about the accuracy of these findings have arisen, particularly due to potential biases in trial blinding and patient expectations. Notably, only one double-blind trial has directly compared psilocybin with escitalopram, showing a greater efficacy for psilocybin.
Given these concerns, further research is crucial to determine the true efficacy of psychedelics, as current evidence may be influenced by compromised blinding and the psychological support provided in these trials.
About the Study
The study followed a rigorous protocol, registered with the International Prospective Register of Systematic Reviews (PROSPERO), and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for network meta-analyses. The researchers conducted an exhaustive search of multiple databases, including Medline, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL), covering studies published up until October 12, 2023.
Eligible studies included randomized controlled trials (RCTs) involving adults diagnosed with depression or depressive symptoms related to life-threatening conditions. The trials analyzed involved oral monotherapy with psychedelics such as psilocybin, MDMA, LSD, ayahuasca, or escitalopram, with concurrent antidepressant use excluded.
The primary outcome measured was the change in depressive symptoms, assessed using validated scales like the 17-item Hamilton Depression Rating Scale (HAMD-17). Secondary outcomes considered were all-cause discontinuation and the occurrence of severe adverse events.
Study Findings
Out of 3,104 unique studies identified through the database search, 19 were ultimately included in the analysis. These studies encompassed 15 trials involving 811 participants who received psychedelic treatments, with an average age of 42.5 years and 54.2% being women. In comparison, 1,968 participants were involved in escitalopram trials, with an average age of 39.4 years and 62.5% being women.
The analysis found that most psychedelic interventions, except for extremely low and low doses of MDMA, demonstrated a mean difference exceeding the minimal important difference of three points on the HAMD-17 scale compared to placebo. High-dose psilocybin, in particular, showed a significant effect size when compared to both escitalopram and placebo. However, this effect size decreased from large to small when placebo was used as the reference.
When focusing solely on patients with major depressive disorder, sensitivity analyses reaffirmed the superiority of high-dose psilocybin and ayahuasca over placebo in antidepressant trials. These findings were consistent across various analyses, including adjustments for baseline depression severity and exclusion of high-risk bias studies.
Importantly, no psychedelic intervention was associated with higher risks of all-cause discontinuation or severe adverse events compared to placebo. Statistical analyses also indicated no publication bias, and the reliability of the findings was supported by the GRADE assessment, which reported moderate to low certainty of evidence across treatment comparisons.
Conclusion
The study concludes that high-dose psilocybin demonstrates greater effectiveness than escitalopram in treating depressive symptoms, with a minimally important difference of three points on the HAMD-17 scale. Among the psychedelics studied, only high-dose psilocybin consistently outperformed escitalopram.
These findings suggest that high-dose psilocybin, particularly when combined with psychotherapeutic support, may offer a promising alternative to traditional antidepressants in the treatment of depression. Further research is warranted to explore this potential and to address the current limitations in the evidence base.